Trident is an American system. It’s really-really-well-made; End-of-Empire best-of-kind product, so expensive that we had to share costs with our “special friends”.
Brit’s do HumInt better than the US does, esp. regarding British nationals, so they will do their jobs. The re-entry vehicles will find their targets, and the bombs will do their missions. That’s a lot of energy locked up in fancy hardware.